The radio-modems used for the radio links between the Bar Beacon and the RNLI Station,
Hayling Island, were kindly donated by Wood and Douglas Limited, a Solent-based supplier of communications
equipment.

The sensors on the Bar Beacon, the associated datalogger, and the software applications
used to analyse the data, were supplied and installed by Campbell Scientific Limited

Emworx Limited on
Hayling Island, have given advice on system design, built the web site and supplied
hosting facilities.

Chimet Support Group is responsible for the design
and development of the overall system, its project management, and the development
of the software used for data control and presentation.

Sensors and Data Reporting

The Web site is updated every 5 minutes from the data collection site at the RNLI
Station, Hayling Island

The link to tidal predictions (in the Latest Report page) is from the United Kingdom
Hydrographic Office Position coordinates (latitude and longitude) are referred to
WGS84 chart datum.

Tidal heights are reduced to Chart Datum, which is approximately the level of Least
Astronomical Tide.

The following table shows briefly how the reported data is derived.

Measurement

Sensor

Sampling Frequency

Averaging

Reporting Interval

Wind Speed

Anemometer

Every second

5 minutes

Every 5 minutes

Wind Gust

Anemometer

Every second

Taking max of 3-second running average

Every 5 minutes

Wind Direction

Wind Vane

Every second

Vector addition over
5 minutes

Every 5 minutes

Air Temperature

Thermistor

Every second

5 minutes

Every 5 minutes

Sea Temperature

Thermistor

Every second

5 minutes

Every 5 minutes

Barometric Pressure

Barometric
Pressure Transducer

Every
minute

5 minutes

Every 5 minutes

Tidal Height

Pressure Transducer

Every second

5 minutes

Every 5 minutes

Wave Height(average)*Note 1

Pressure Transducer

Every second

15 minutes

Every 5 minutes

Wave Height(maximum)*Note2

Pressure Transducer

Every second

15 minutes

Every 5 minutes

Wave Period*Note 3

Pressure Transducer

Every second

15 minutes

Every 15 minutes

*Note 1 - Wave height is calculated by subtracting
the minimum water depth from the maximum water depth. An average is then taken over
15 minutes.

*Note 2 - Maximum wave height is calculated
by subtracting the minimum water depth from the maximum water depth. The maximum
is then recorded.

*Note 3 - Wave period is calculated by taking
a Fast Fourier Transform on 512 consecutive samples of the water depth. A spatial
maximum is then performed on the resulting histogram. This gives the bin with the
greatest frequency. The frequency is calculated from the bin number. Wave periodicity
is the reciprocal of this. The number of samples has been limited by the available
battery power at the Bar Beacon.